1. Field of the Invention
The present invention relates to installation of conduit within confined spaces behind walls of commercial or residential buildings; and more particularly to a method and means for stringing up new or additional telecommunication wires, optical cables or electrical wiring behind sheetrock or plaster walls in existing homes or office buildings, without having to open out or cut pathways for the wire.
2. Description of the Prior Art
Those responsible for construction and maintenance of homes and commercial buildings have long struggled to devise a method and means for addressing the difficult task of bringing in new wires for electrical service. They are also tasked with the charter of providing high-speed Internet capability using telecommunication wires or optical cables without having to tear up existing walls and ceilings. Generally, installation includes tearing up of progressive slots or holes in the ceiling or walls to enable the telecommunication, optical or electrical wiring to be drawn from one inlet location to a second outlet location. After the installation work is complete, the sheetrock or plaster must be resurfaced to obtain a suitable finish for repainting. This string-up process is wasteful, consuming time, energy and expense.
U.S. Pat. No. 1,130,775 to I. J. Hi Toffey discloses a wire finding and coupling device. The device comprises a projectile shaped body having three spring-loaded wing arms, which flex so that a fishing cable can be freely inserted into a conduit. After the projectile goes around a bend in the conduit, it can be snagged using a hook and threaded into the conduit. The Toffey device is a wire finding and coupling device that sends a wire through a conduit in spite of bends in the conduit. The wire moves readily into the conduit and can be fished using a snagging hook. For operation, the device requires the presence of a pre-drawn conduit behind the walls. Accordingly, the device does not thread a telecommunication or electrical wire within a free space extant between building structure and the back of a sheetrock or plaster wall.
U.S. Pat. No. 2,923,528 to W. A. Komorski discloses an electrician's fishing tool. The electrician's fishing tool consists of a wire that is fabricated from three strands of oppositely wound wire. With this construction, the wire elongates minimally upon application of a load thereto; it transmits twisting motion across the long wire due to the opposite windings. One end of the braided wire is anchored to an ordinary wire using a clamp formed by producing a fork. The fork clamps the braided wire, transmitting twist motion. Such an arrangement facilitates snaking of braided wire through bends in a conduit, which may have many bends, is occasionally pinched, and may have a few nails extending therethrough. Like Toffey, Komorski's requires the presence of a pre-drawn conduit behind the walls. Accordingly, the Komorski device does not thread a telecommunication or electrical wire within a free space extant between building structure and the back of a sheetrock or plaster wall.
U.S. Pat. No. 3,078,073 to T. J. Zizzo discloses an electrical wire finder. The electrical wire is attached to a conductor holder with a screwed fastener and inserted through a wall opening for an electrical outlet. The top portion of the conductor holder carries a powerful permanent magnet. A flexible string is attached to a sensor made from magnetizable material, such as steel, and is lowered from the attic in the same bay. When the sensor element comes in close proximity with the permanent magnet, it is attracted and is held securely by the permanent magnet. Pulling on the flexible string then drags the wire functioning as a wire stringing apparatus. If excessive force is used during pulling of the string, or if the electrical wire offers excessive resistance, the magnet may let go, breaking the guided pull. Operational reliability thus presupposes lack of resistance of the wire to the pulling process, which is oftentimes not present during all installation conditions.
U.S. Pat. No. 3,971,543 to Shanahan discloses a tool and kit for electrical fishing. A magnetically attractable body is hung on a chain formed from spherical elements connected by studs; and the structure is hung on a string from an eyelet. The chain can swing readily to contact a magnet. A magnet body is inserted at the wall receptacle and carries the magnet. When the spherical element is attracted to the magnet, it is audible and can be pulled down to have a continuous string from the starting point to the end point. A wire can be pulled through when it is attached to the string, which facilitates threading of an electrical wire. The swinging ability of spherical element reduces the need to aim the magnetizable element very close to the magnet. These additional elements increase the cost and decrease reliability of the Shanahan device. The magnetically attractable element of the Shanahan device is not guided by a magnet; but is captured by a magnet inserted inside the wall.
U.S. Pat. Nos. 4,527,775 and 4,618,124 to Flowers disclose an apparatus for installing a conduit. A tape with a magnetically attractable roller is first inserted through an opening in an attic. The tape is guided to its destination behind a wall, using an electromagnet mounted on wheels, which rides on the interior wall. The electromagnet attracts the roller carrying the tape and guides it downward to its destination as the electromagnet is moved. Once the tape is brought through, the conduit is firmly attached to the tape and is pulled through behind the wall. The Flowers device is an apparatus for installing conduits in pre-existing buildings behind the sheetrock in a wall. The reduced friction of the roller at the end of the tape allows free rolling of the rollers on the inner surface of the wall, and it is guided to its destination by the electromagnet on rollers riding on the interior wall. The electromagnet in the Flowers device does not contact the interior wall, since it is riding on the rollers. As a result, the distance between the magnet and the attracted magnetizable body within the interior of the walls is larger than the thickness of sheetrock. In addition, the electromagnet is generally weak, especially at increased distance between the electromagnet and the magnetizable body, and consumes battery power resulting in reduced battery service life. The distance between the electromagnet and the magnetizable body is lowest when each is aligned in the same vertical plane; and any departure of these two elements increases their relative distance, resulting in even weaker attraction. Accordingly, the tape-carrying roller tends to lose contact with the inner wall and wander, resulting in unreliable string-up attempts.
U.S. Pat. No. 4,572,561 to Hale discloses a tool for magnetically locating and recovering electrical wires. A magnet is attached to the end of a wire being fished. Another magnet is surrounded by cork or wood, so that it is buoyancy neutral when suspended in a liquid. When the magnet suspended in a buoyant liquid is brought close to the interior wall, the floating magnet indicates the lateral position of the end of the wire with the attached magnet is located within the sheetrock or plaster wall. Once the position of the end of the wire is known, it is easy to drill a hole to fish the wire through. This procedure only locates the wire; it does not guide the wire from one point to another point. Accordingly, the method disclosed by Hale requires cutting or drilling holes in-between the two points.
U.S. Pat. No. 5,261,714 to Slusar et al. discloses an electromagnetic pick-up tool. This tool uses an elongated flexible tubular conductive shaft, which carries an electromagnet on one end. Batteries on the other end power the electromagnet. The flexible shaft is inserted to retrieve magnetizable objects. No disclosure is contained in Slusar et al. concerning a string up device for inserting electrical wires behind a sheetrock wall.
U.S. Pat. No. 5,440,297 to Bright discloses an electrician's fish tape locator system. The fish tape locator system comprises a transmitter assembly and a receiver to determine when the fish tape that is forced through the conduit has reached a terminus. The transmitter assembly is mounted at the conduit terminus and the fish tape is inserted from the other end, where the electrician is forcing the fish tape. The end of the fish tape activates a contact switch and the transmitter. A receiver in close proximity to the electrician receives the transmitted signal, activating an audio indication. Bright's device aids the electrician by determining when to stop pushing the fish tape through a conduit. It does not assist with pushing electrical wire behind a sheetrock wall, when no conduit is present.
U.S. Pat. No. 5,522,630 to James discloses a fishing tool for magnetic objects. The tool consists of an electromagnet powered by a variable power DC battery source. In one embodiment, an electromagnet is attached to a string using an eyelet formed on the electromagnet. The assembly is lowered from an upper hole into a bay between joists disposed behind a sheetrock or plaster wall. A magnetizable fish tape is inserted in a lower hole in the same bay, and the electromagnet is energized using the variable DC power supply. The electromagnet attached to the string attracts and captures the fish tape. Each of the fish tape and the electromagnet is pulled through the lower hole, completing the string up operation. In a second embodiment, the fish tape is secured to a slot in the fishing tool, and is held by screws. The fishing tool, with the attached fish tape, is pushed up through the conduit from the lower hole and energized by the variable power DC source. A magnetizable fishing tape is inserted from the top to contact the energized fishing tool and capture it. The fishing tape together with the fishing tool is pulled through the upper hole. This attraction completes the fishing operation and the wire can be pulled through. In both cases, a tool is energized by a variable power electromagnet attracting a magnetizable article inserted at the upper hole or lower hole and relies on a secure attachment between the energized electromagnet and magnetizable fish to complete the fishing operation. Since the electromagnet used in the first embodiment is heavy and carried by a flexible string, it can swing and may not easily contact the inserted fish tape at the lower hole, especially if the upper and lower holes are not aligned in a vertical plane. In the second embodiment, the heavy electromagnet is essentially carried by the fish tape, attached by screws in an asymmetric configuration, and has to carry the electrical leads. This configuration allows bending and collapse of the fish tape. It may not be inserted vertically, thereby impairing its ability to contact the inserted magnetizable fish tape at the upper hole. With either embodiment, the magnetizable object and the electromagnet must be in close proximity to create contact. In addition, the electromagnet must sustain the weight of the electromagnet and fish tape during pull. Such sustained contact is oftentimes not readily accomplished, and requires a high current that is not easily provided by a battery power source.
U.S. Pat. No. 6,257,808 to Groot discloses a wall fishing apparatus. It uses a long flexible shaft and work engaging means to insert a drill bit on the distal end of the flexible shaft. The other end of the flexible shaft is connected to a hand drill. The device is designed to drill holes in inaccessible cross members, which essentially obstruct the ability to pass a conduit or wire through the wall behind the sheetrock. A threading means for passing wire or conduit through the drilled hole is disclosed. This actively clears the way for inserting a wire or conduit through behind a sheetrock or plaster wall, but does not provide the functionality of stringing up a telecommunication or electrical wire.
There remains a need in the art for an effective apparatus for fishing telecommunication wires, optical cables or electrical wiring through a bay between joists behind a sheetrock or plaster wall without having to drill multiple holes or create slots along the Wire path. Such drilling and cutting operations mar the appearance of the wall and require a refinishing operations wherein plaster is reapplied to regain an appropriate wall substrate appearance and the wall is thereafter repainted or wall papered. Such refinishing operations are time consuming and expensive.